Question

One of your friend has a habit of writing on walls. He spoils school's property. Discuss this problem and decide what you can do to make him realise about his fault.

Answer 1

You can make him feel that he wrong in spoiling school's property by writing on it :-
1-By explaining him that it's wrong 
2-By presenting some good example's to him
3-By snatching pen's or pencil when he is writing on the walls
4-By complaining to your teacher 
5-you can make him realize by when you see or caught him writing on wall you can act as you are not talking to him and tell ur all friends not to talk to him when he feel lonely he'll leave his bad habit

Answer 2

if your friend spoils school's property so you can make him understand poliety and tell him that it is not good to damage the school property. you can tell him that if you keeps your home neat and clean, so why can't you keep your school neat and clean. we come here to study we are not coming here to spoil the school property. and if by making him understand poliety he is not changing his attitude towards cleanliness of school so you can take an action that:

you can complain to the teacher,
you can take fine from him because he is damaging the school property,
you can teach him a lesson like. you can write on his book and if he gets angry so you can say that if you write on school wall so are we filling pleased no friend just for making you understand we did this and we are sorry for this.
so, by this may your friend understand his problem and try not to do this again.